1. Field of the Invention
The present invention generally relates to hydraulic compression tools and, more particularly, to drives for hydraulic compression tools having rotary motors.
2. Brief Description of Earlier Developments
Hydraulic power tools are used in numerous applications to provide users with a desired mechanical advantage. One such application is in crimping tools used for making crimping connections, such as for example, crimping power connectors onto conductors, or grounding connectors onto grounding wires. Other applications include jacking devices, presses and so on. In these cases, many operators desire that the hydraulic tools be powered, or in other words that the hydraulics be actuated by a motor merely at the flip of a switch or the press of a button. Naturally, a powered hydraulic tool does away with manual pumping by the operator to actuate the hydraulics, and hence, involves much less physical effort on the part of the operator to operate the tool. In addition to the significantly smaller physical effort, another desired advantage of the powered hydraulic tool compared to manual hydraulic tools, is that the powered tool may be faster. This allows tasks to be accomplished with the tool to be completed faster with a resulting reduction in cost. Indeed, for portable hydraulic tools, such as for example, hydraulic crimping tools, which are held and supported in the hands of the operator, the operating speed (e.g. how quickly the hydraulic ram is traversed through its stroke) of the tool becomes even more important. The quicker the task can be completed, the sooner the operator can put the tool down. Powered hydraulic tools are more complex, and hence more expensive as a rule, than their manually actuated counterparts. The added complexity may also tend to make powered hydraulic tools more susceptible to breakdown. This may be frustrating to the operator, as well as costly especially for tools used in the field where repair may not be readily available. Conventional powered hydraulic tools which employ a piston pump to operate the hydraulics generally may have a spring loaded piston to provide impetus to the piston in at least one direction and/or a camming mechanism capable of reciprocating the piston during operation.
U.S. Pat. No. 6,206,663 discloses one example of a piston pump for a hydraulic tool wherein the pump has a low-pressure delivery piston which is spring loaded to drive the piston to achieve fluid delivery at low pressure. The low pressure piston is moved back counter to the spring load prestress by a high pressure piston moved by a rotating shaft.
Another example is disclosed in U.S. Pat. No. 5,727,417 in which the hydraulic drive tool has a drive assembly with a wobble plate providing axial displacement to a spring loaded piston. The spring preload on the pistons returns the pistons to a fluid delivery starting position. Still other examples are disclosed in U.S. Pat. Nos. 5,111,681 and 5,195,354 in which a motor driven hydraulic tool has a motor operatively connected to a hydraulic pump via a cam link mechanism. The cam link mechanism has a plunger with a ring shaped fitting portion which has an eccentric shaft fitted therein to rotate freely.
The present invention overcomes the problems of conventional hydraulic tools as will be described in greater detail below. In accordance with one aspect of a preferred embodiment, the piston pump is springless, reciprocated by a cam link mechanism to the motor without assistance from spring preload. Moreover, in accordance with another aspect of the preferred embodiment, the cam link mechanism between the motor and piston is simple to manufacture and install, employing large bearing surfaces which reduces the cost of the tool while increasing reliability. These aspects as well as others will be described in greater detail below.
In accordance with a first embodiment of the present invention, a hydraulic tool drive is provided. The hydraulic tool drive comprises a frame, a hydraulic ram, a pump, a motor, and a link. The frame has a hydraulic reservoir. The hydraulic ram is movably mounted to the frame. The pump has a pump piston for pumping hydraulic fluid to move the hydraulic ram relative to the frame. The motor is connected to the frame. The motor has an output shaft which rotates about an axis of rotation when the motor is operating. The link operably connects the output shaft to the pump piston for generating a reciprocating movement of the pump piston relative to the pump when the motor is operated. The link is rotatably mounted on the output shaft and is pivotable at least at one end relative to the frame, wherein at least one end of the link is pivotally connected to the pump piston by a pin.
In accordance with another embodiment of the present invention, a hydraulic tool drive is provided. The tool drive comprises a frame, a hydraulic ram, a pump, a motor, and a collar. The frame has a hydraulic reservoir. The hydraulic ram is moveably mounted to the frame. The pump is connected to the frame. The pump has a pump piston for pumping hydraulic fluid to move the hydraulic ram relative to the frame. The pump piston is moveable relative to the pump along an axis of translation. The motor is connected to the frame. The motor has a rotary output shaft. The collar is connected to the rotary output shaft and has a joint at which the collar is moveably joined to the pump piston to move relative to the pump piston along another axis of translation which is substantially orthogonal to the axis of translation of the pump piston, wherein the collar comprise a frame with a generally cylindrical bore in which the rotary output shaft is eccentrically located, the frame having a clevis at one end which forms the joint in the collar.
In accordance with another embodiment of the present invention, a hydraulic tool drive is provided. The tool drive comprises a frame, a hydraulic ram, a pump, a motor, and a collar. The frame has a hydraulic reservoir. The hydraulic ram is moveably mounted to the frame. The pump is connected to the frame. The pump has a pump piston for pumping hydraulic fluid to move the hydraulic ram relative to the frame. The pump piston is moveable relative to the pump along an axis of translation. The motor is connected to the frame. The motor has a rotary output shaft. The collar is connected to the rotary output shaft and has a joint at which the collar is moveably joined to the pump piston to move relative to the pump piston along another axis of translation which is substantially orthogonal to the axis of translation of the pump piston, wherein the drive further comprises an eccentric fixedly mounted to the rotary output shaft, the eccentric being engaged to the collar so that when the motor rotates the rotary output shaft the collar is moved in an orbital motion relative to the output shaft.
In accordance with still another embodiment of the present invention, a hydraulic crimping tool is provided. The tool comprises a frame, a hydraulic ram, a pump, a motor, and a transmission. The frame has a hydraulic reservoir. The hydraulic ram is movably mounted to the frame. The pump is connected to the frame. The pump has a pump piston for hydraulically moving the hydraulic ram relative to the frame. The motor is connected to the frame. The motor has a rotary output shaft to the pump piston. The transmission comprises an eccentric. The eccentric is fixable mounted onto the rotary output shaft. The transmission comprises a collar rotatable mounted onto the eccentric to rotate relative to the eccentric. The collar is movably joined to the pump piston, wherein the collar has a clevis, the pump piston being pinned to the collar in the clevis.
In accordance with yet another embodiment of the present invention, a transmission for connecting a rotary motor output shaft to a rectilinear actuator which is movable rectilinearly along an actuator axis of translation is provided. The transmission comprises a frame, an eccentric, and a rectilinear guide. The frame has a bore formed therein. The eccentric is adapted to position the frame on the rotary motor output shaft. The eccentric is rotatably mounted in the bore of the frame to rotate relative to the frame. The rectilinear guide is connected to the frame. The rectilinear guide has a slide surface adapted to slidably seat against the rectilinear actuator allowing the frame to slide substantially rectilinearly relative to the rectilinear actuator, wherein the frame has a recess formed therein, the recess being sized and shaped for movably locating at least part of the rectilinear actuator in the recess, the rectilinear guide extending across the recess.
In accordance with a further embodiment of the present invention, a hydraulic tool drive is provided. The hydraulic tool drive comprises a frame, a hydraulic ram, a pump, a motor, and a link. The frame has a hydraulic reservoir. The hydraulic ram is movably mounted to the frame. The pump has a pump piston for pumping hydraulic fluid to move the hydraulic ram relative to the frame. The motor is connected to the frame. The motor has an output shaft which rotates about an axis of rotation when the motor is operating. The link operably connects the output shaft to the pump piston for generating a reciprocating movement of the pump piston relative to the pump when the motor is operated. The link is rotatably mounted on the output shaft and is pivotable at least at one end relative to the frame, wherein the link has an end which is movably mounted to the pump piston so that the link moves freely relative to the pump piston.
In accordance with another embodiment of the present invention, a hydraulic tool drive is provided. The hydraulic tool drive comprises a frame, a hydraulic ram, a pump, a motor, and a link. The frame has a hydraulic reservoir. The hydraulic ram is movably mounted to the frame. The pump has a pump piston for pumping hydraulic fluid to move the hydraulic ram relative to the frame. The motor is connected to the frame. The motor has an output shaft which rotates about an axis of rotation when the motor is operating. The link operably connects the output shaft to the pump piston for generating a reciprocating movement of the pump piston relative to the pump when the motor is operated. The link is rotatably mounted on the output shaft and is pivotable at least at one end relative to the frame, wherein the link has a recess at one end, at least one end of the pump piston being located in the recess.
In accordance with yet another embodiment of the present invention, a transmission for connecting a rotary motor output shaft to a rectilinear actuator which is movable rectilinearly along an actuator axis of translation is provided. The transmission comprises a frame, an eccentric, and a rectilinear guide. The frame has a bore formed therein. The eccentric is adapted to position the frame on the rotary motor output shaft. The eccentric is rotatably mounted in the bore of the frame to rotate relative to the frame. The rectilinear guide is connected to the frame. The rectilinear guide has a slide surface adapted to slidably seat against the rectilinear actuator allowing the frame to slide substantially rectilinearly relative to the rectilinear actuator, wherein the rectilinear guide comprises a pin, an outer surface of the pin forming the slide surface.